The present invention relates to a radio-frequency hybrid switch module for use in mobile communications equipment including a mobile phone.
FIG. 1 is a circuit block diagram of an antenna duplexer used in a GSM/DCS dual-band mobile phone conforming to European standards for mobile communications based on a Time Division Multiple Access system. The antenna duplexer includes antenna terminal 1, GSM-band transmitting (GSM-TX) terminal 2, GSM-band receiving (GSM-RX) terminal 3, DCS-band transmitting (DCS-TX) terminal 4, DCS-band receiving (DCS-RX) terminal 5, diplexer 6 for separating and combining frequency components in GSM and DCS bands, switches 7, 8 for switching between transmission and reception, low pass filters (LPFs) 9, 11 for removing unwanted harmonic signals, and surface acoustic wave (SAW) filters 10, 12 for allowing a band of received frequencies to pass.
FIG. 10 shows a structure of a conventional antenna duplexer. This antenna duplexer includes ceramic multi-layer substrate 18, alumina package 19, SAW device chip 20, bonding wire 21, lid 22 of alumina package 19, diodes 23 functioning as switching devices, chip devices 24, pad 25 formed on the alumina package for wire bonding, and metal cap 26. Ceramic multi-layer substrate 18 includes a LPF and a diplexer formed therein.
In the duplexer described above, SAW chip 20 is put in alumina package 19 and mounted over ceramic multi-layer substrate 18. Alumina package 19, for being sealed hermetically with lid 22, needs to has a wall thickness 19a ranging from about 0.5 mm to 1.0 mm, Thus hardly having a reduced size.
A small radio-frequency (RF) hybrid switch module is provided for switching between transmit-signals and receive-signals in plural frequency bands.
This module includes: a laminated body having a dielectric layer; a diplexer; a switching circuit; a low pass filter (LPF); a conductive pattern on the dielectric layer for forming at least one of the diplexer, the switching circuit and the LPF; a surface acoustic wave (SAW) filter mounted on the laminated body; a cover on the SAW filter for forming a cavity which allows surface acoustic wave vibration and hermetically sealing the cavity, and a semiconductor switching device mounted on the laminated body for forming a part of the switching circuit.